In the conventional rotary lawn mower the engine is mounted on a housing and the drive shaft extends downwardly within the housing and is operably connected to one or more rotary blades. Larger sized rotary lawn mowers are frequently self-propelled in which an auxiliary drive connects the engine drive shaft with the wheels to drive the lawn mower across the ground. With the conventional self-propelled rotary mowers, the drive to the cutting blade is independent of the wheel drive so that if the forward motion of the mower is stopped, the blade will continue to operate, thereby presenting a potential hazard to the operator who may occasionally attempt to reach under the mower when the mower is stopped to remove objects from the housing.
Recently, there has been increased interest in controlling noise pollution of lawn mowers and many attempts have been made to reduce the noise level by use of more elaborate and effective muffler systems. The noise level controls have not been entirely successful, in that they have either been inefficient or exceedingly costly to incorporate with a conventional type mower.